Interface changes for getImageDomainsList internal changes.

Complement to I25fe2714e4c4e832230653cebc87d8da0e81028b.

Change-Id: Ib4cbfe95359defb14263ff5566e62e6f01c7d54a
Signed-off-by: Eduardo <ewarszaw@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16090
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>